The present invention relates to a semiconductor integrated circuit device and a wireless communication system. More particularly, the present invention relates to a wireless communication system that isolates a transmission signal and a received signal with a duplexer, and to an effective technology applicable to a high-frequency signal processing LSI that serves as a part of the wireless communication system and provides conversion between a high-frequency signal and a baseband signal.
In a configuration described, for instance, in a document titled “A 90 nm CMOS Direct Conversion Transmitter for WCDMA,” Radio Frequency Integrated Circuits (RFIC) Symposium, 2007 IEEE, by Xuemin Yang and three other authors, a duplexer is disposed between a transmission power amplifier circuit and a reception low-noise amplifier (LNA) circuit to isolate a transmission signal from a received signal. In a configuration described, for instance, in a document titled “A Split Band Duplexer for PCS CDMA Mobile Phones,” Radio and Wireless Conference, 2004 IEEE, by Torsten Keiler and another author, the band for transmission signals is split into two segments so that each transmission signal is coupled to one antenna port through an SPDT (Single-Pole Double-Throw) switch.